My question is as stated above, do all black holes spin the same direction?
To my knowledge, the spin in the direction of the spin of the matter that created them. Another similar question was asked here, regarding whether they spin clock-wise or counter clock-wise, and the answer was that it was irrelevant, and dependent upon the position of the looker.
My question is more specifically, are all black holes existent, spinning in the same direction?
Basis an intuition around, all matter/space/time is expanding outward in a similar fashion from the start point (not a fixed point in space I realize) of the universe. So does that mean that all matter inherently spins around a central axis from which the universe expanded from? In this case, all black holes would seem to be rotating along similar parameters, as all the matter that could create them are spinning as such. However I do not know enough on the details of the universal expansion nor black holes to confirm this.
To end, consider that two black holes are spinning in opposite directions, observed from the position of an observer looking at an xy-plane, one would be spinning from higher to lower numbers on the x axis and the other from lower to high numbers on the x axis, and assume both were at a fixed line on the y axis.
Best Answer
You wrote:
And then:
But these are contradictory statements. There is no central point or central axis and all matter isn't in orbit / rotating around some fixed center. See this for details.
The spin of one black hole relative to another is completely random (assuming they didn't both form from related source material like the same galactic disk). As @dmckee pointed out, the spin of an isolated black hole is dependent on an arbitrary choice of reference frame so all that matters is the spin of one relative to another. Their spin direction is not correlated in any way.